During metal machining, the satisfactoriness of cost-quality-time matrix convergence effectively depends on the supreme selection of cutting parameters. This study investigated the energy use minimisation and quality ...During metal machining, the satisfactoriness of cost-quality-time matrix convergence effectively depends on the supreme selection of cutting parameters. This study investigated the energy use minimisation and quality surface generation through optimised cutting parameters application, as sustainability enhancement during dry turning of EN19 material. Cutting parameter optimisation is a serious challenge confronting the machining industry as they strive to achieve low energy use and better component quality generation from their operations. The utility material, EN19, is a medium-carbon low alloy steel which typically gets applied in the manufacturing of multiple profiled cylindrical machine tool, rail locomotives and motor vehicle component parts, inter alia. Taguchi Full Factorial experimental plan was used to organise the empirical experiments. ANOVA and the main effects plot signal-to-noise ratio optimisation analysis were utilised in the study to establish the influence of process parameters on the response parameters—surface roughness and energy use. The aim was to investigate and determine the correlation of the machining strategy parameters with the outcome of low energy use and quality surface texture of the components as the cutting parameters were varied, and optimised for minimum surface roughness and energy use. Results of the extensive experimental study, produced optimum cutting speed, rake angle variation and feed rate which respectively influence the response parameters positively for energy use minimisation and improved surface quality. Validation experiments confirmed model findings.展开更多
With the support by the National Natural Science Foundation of China,the research team led by Prof.Wei Chu(魏楚)and Prof.Zheng Xinye(郑新业)at the Department of Energy Economics,School of Economics,Renmin University o...With the support by the National Natural Science Foundation of China,the research team led by Prof.Wei Chu(魏楚)and Prof.Zheng Xinye(郑新业)at the Department of Energy Economics,School of Economics,Renmin University of China,measures the inequality using the household energy展开更多
National Association for Hydrogen Energy (NAHE) was established in 2003 to facilitate the effective integration of the Russian Federation into the world hydrogen economy. The priority for the Association is to create ...National Association for Hydrogen Energy (NAHE) was established in 2003 to facilitate the effective integration of the Russian Federation into the world hydrogen economy. The priority for the Association is to create legislation and basic standards which necessary for the successful development of hydrogen energy, promote this sector to a large public and to support the development of those priority areas, where Russia has the best prospects to take a rightful place in the international division of labour (atomic hydrogen energy, fuel cells, hydrogen vehicles). Hydrogen Energy, National Association for Hydrogen Energy By now the Association has developed a draft technical regulation on security devices and systems展开更多
Neutral particle energy spectra in the HT-7 tokamak are calculated by using the Monte Carlo method. It can reproduce the spectra measured in experiment. Differences of neutral particle energy spectra in higher and low...Neutral particle energy spectra in the HT-7 tokamak are calculated by using the Monte Carlo method. It can reproduce the spectra measured in experiment. Differences of neutral particle energy spectra in higher and lower electron density plasma are discussed. Results show that the ion temperature given by neutral particle energy spectra is lower than the real ion temperature, but the deviation is within 10% if the ion temperature is less than 800 eV and thecentral chord-averaged electron density does not exceed 3 ×1013 cm-3. But for ion temperature higher than 1000 eV at the central chord-averaged density limit up to 5 ×1013 cm-3, the neutral particle energy spectra can still give the ion temperature within 10% deviation.展开更多
The California Simulation of Evapotranspiration of Applied Water (CaI-SIMETAW) model is a new tool developed by the California Department of Water Resources and the University of California, Davis to perform daily s...The California Simulation of Evapotranspiration of Applied Water (CaI-SIMETAW) model is a new tool developed by the California Department of Water Resources and the University of California, Davis to perform daily soil water balance and determine crop evapotranspiration (ETo), evapotranspiration of applied water (ETaw), and applied water (AW) for use in California water resources planning. ETaw is a seasonal estimate of the water needed to irrigate a crop assuming 100% irrigation efficiency. The model accounts for soils, crop coefficients, rooting depths, seepage, etc. that influence crop water balance. It provides spatial soil and climate information and it uses historical crop and land-use category information to provide seasonal water balance estimates by combinations of detailed analysis unit and county (DAU/County) over Califomia. The result is a large data base of ETc and ETaw that will be used to update information in the new California Water Plan (CWP). The application uses the daily climate data, i.e., maximum (Tx) and minimum (Tn) temperature and precipitation (Pcp), which were derived from monthly USDA-NRCS PRISM data (PRISM Group 2011) and daily US National Climate Data Center (NCDC) climate station data to cover California on a 4 kmx4 km change grid spacing. The application uses daily weather data to determine reference evapotranspiration (ETo), using the Hargreaves-Samani (HS) equation (Hargreaves and Samani 1982, 1985). Because the HS equation is based on temperature only, ETo from the HS equation were compared with CIMIS ETo at the same locations using available CIMIS data to determine correction factors to estimate CIMIS ETo from the HS ETo to account for spatial climate differences. CaI-SIMETAW also employs near real-time reference evapotranspiration (ETo) information from Spatial CIMIS, which is a model that combines weather station data and remote sensing to provide a grid of ETo information. A second database containing the available soil water holding capacity and soil depth information for all of California was also developed from the USDA-NRCS SSURGO database. The Cal-SIMETAW program also has the ability to generate daily weather data from monthly mean values for use in studying climate change scenarios and their possible impacts on water demand in the state. The key objective of this project is to improve the accuracy of water use estimates for the California Water Plan (CWP), which provides a comprehensive report on water supply, demand, and management in California. In this paper, we will discuss the model and how it determines ETaw for use in water resources planning.展开更多
With rapid economy growth,building energy consumption in China has been gradually increased.The energy consumption and indoor environmental quality of 51 office buildings in Hainan Province,a hot and humid area,were s...With rapid economy growth,building energy consumption in China has been gradually increased.The energy consumption and indoor environmental quality of 51 office buildings in Hainan Province,a hot and humid area,were studied through collection of verified data in site visits and field tests.The result revealed that,electricity accounted for 99.79% of the total energy consumption,natural gas 0.17%,and diesel 0.04%.The air conditioning dominated the energy use with a share of 43.18%,equipment in the particular areas 26.90%,equipment in the office rooms 11.95%,lighting system 8.67%,general service system 7.57%,and miscellaneous items 1.73%.Statistical method including six indicators obtained the energy consumption benchmark with upper limit of 98.31 kW-h/m2 and lower limit of 55.26 kW-h/m2.According to ASHRAE standard(comfortable standard) and GB/T 18883-2002(acceptable standard),the indoor environmental quality of 51 sampled office buildings was classified into three ranks:good,normal and bad.With benchmark of building energy consumption combined with indoor environmental quality,it was found that only 3.92% of sampled buildings can be identified as the best performance buildings with low energy consumption and advanced indoor environmental quality,and the buildings classified into normal level accounted for the maximum ratio.展开更多
Two spherically symmetric non-singular black hole solutions in Moiler tetrad theory of gravitation have been obtained. Although the two solutions have the same form of metric (spherically symmetric nonsingular black ...Two spherically symmetric non-singular black hole solutions in Moiler tetrad theory of gravitation have been obtained. Although the two solutions have the same form of metric (spherically symmetric nonsingular black hole), their energy contents are different. We use another method given by Gibbons and Hawking to calculate the energy content of these solutions. We also obtained different value of energy. Study the requirements of a satisfactory energymomentum complex given by Moiler we find that the second solution, which behaves as 1/√r, is not transformed as a four-vector under Lorentz transformation.展开更多
The literature that a lack of integration between the performance shaping factors(PSFs)and the energy management performance(EMP)is one of the critical problems that prevent performance improvement and reduces the pow...The literature that a lack of integration between the performance shaping factors(PSFs)and the energy management performance(EMP)is one of the critical problems that prevent performance improvement and reduces the power plant’s efficiency.To solve this problem,this article aims to achieve two main objectives:(1)Systematically investigate and identify the critical success factors(CSFs)for integration with PSFs and EMP;(2)Develop a novel modelling approach to predict the performance of power plants based on innovative integrated strategies.The research methodology is grounded on the theoretical and practical approach to improving performance.The Newcastle Ottawa Scale(NOS)was used to assess the quality of the literature that met the criteria.To ensure the reliability and accuracy of the proposed model,the researchers developed a hypothesis and evaluated the CSFs via a case study in the Iraqi power plants.The findings of this study succeeded in developing a novel modeling approach to predict the performance by integrating the CSFs of both the PSFs and EMP to increase the positive interaction and energy efficiency of power plants.The results confirmed the validity of the selected hypotheses and verified the positive and important relationship with the success and improvement of the performance in power plants.However,the lack of consistency and balance in the current studies indicates that the performance strategy in power plants did not receive sufficient attention and needs further investigations.展开更多
High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner(AC)in warm and humid regions.This study aims to evaluate the techno-financial asp...High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner(AC)in warm and humid regions.This study aims to evaluate the techno-financial aspects of the AC-cooled greenhouse as compared to the evaporative cooled(EV-cooled)greenhouse in winter and summer seasons.Two quonset single-span prototype greenhouses were built in the Agriculture Experiment Station of Sultan Qaboos University,Oman,with dimensions of 6.0 m long and 3.0 m wide.The AC-cooled greenhouse was covered by a rockwool insulated polyethylene plastic sheet and light emitting diodes(LED)lights were used as a source of light,while the EV-cooled greenhouse was covered by a transparent polyethylene sheet and sunlight was used as light source.Three cultivars of high-value lettuce were grown for experimentation.To evaluate the technical efficiency of greenhouse performance,we conducted measures on land use efficiency(LUE),water use efficiency(WUE),gross water use efficiency(GWUE)and energy use efficiency(EUE).Financial analysis was conducted to compare the profitability of both greenhouses.The results showed that the LUE in winter were 10.10 and 14.50 kg/m^(2) for the AC-and EV-cooled greenhouses,respectively.However,the values reduced near to 6.80 kg/m^(2) in both greenhouses in summer.The WUE of the AC-cooled greenhouse was higher than that of the EV-cooled greenhouse by 3.8%in winter and 26.8%in summer.The GWUE was used to measure the total yield to the total greenhouse water consumption including irrigation and cooling water;it was higher in the AC-cooled greenhouse than in the EV-cooled greenhouse in both summer and winter seasons by almost 98.0%–99.4%.The EUE in the EV-cooled greenhouse was higher in both seasons.Financial analysis showed that in winter,gross return,net return and benefit-to-cost ratio were better in the EVcooled greenhouse,while in summer,those were higher in the AC-cooled greenhouse.The values of internal rate of return in the AC-and EV-cooled greenhouses were 63.4%and 129.3%,respectively.In both greenhouses,lettuce investment was highly sensitive to changes in price,yield and energy cost.The financial performance of the AC-cooled greenhouse in summer was better than that of the EV-cooled greenhouse and the pattern was opposite in winter.Finally,more studies on the optimum LED light intensity for any particular crop have to be conducted over different growing seasons in order to enhance the yield quantity and quality of crop.展开更多
The Chinese government is developing biomass ethanol as one of its automobile fuels for energy security and environmental improvement reasons. The energy efficiency of the biomass-based fuel ethanol is critical issue....The Chinese government is developing biomass ethanol as one of its automobile fuels for energy security and environmental improvement reasons. The energy efficiency of the biomass-based fuel ethanol is critical issue. To investigate the energy use in the three biomass-base ethanol fuel systems, energy content approach, Market value approach and Product displacement approach methods were used to allocate the energy use based on life cycle energy assessment. The results shows that the net energy of corn based, wheat based, and cassava-based ethanol fuel are 12543MJ, 10299MJ and 13112MJ when get one ton biomassbased ethanol, respectively, and they do produce positive net energy.展开更多
Residential energy consumption is varying considerably worldwide. In order to understand these variations, and thus design effective policies for energy reductions, one needs a better understanding of the different dr...Residential energy consumption is varying considerably worldwide. In order to understand these variations, and thus design effective policies for energy reductions, one needs a better understanding of the different drivers behind these variations. A comparison of geographical areas with similar climate and socio-economic conditions has shown significant variations in residential energy consumption across otherwise comparable case studies. This research paper aims to identify cultural and historical parameters that contribute to these significant variations, including economic, environmental and social traditions related to local availability of natural resources. Furthermore, the transferability of these parameters is evaluated, taking into consideration local legislation and planning documents, and historic and socio-economic accessibility of resources. It is evaluated to which degree these parameters can be transferred and included into building assessment tools and policy documents for planning and transformation of sustainable urban neighborhoods.展开更多
Lighting design is one of the fastest changing areas in building engineering. It has evolved significantly in recent years due to changing technology and demands for improved quality, better control, reduced energy an...Lighting design is one of the fastest changing areas in building engineering. It has evolved significantly in recent years due to changing technology and demands for improved quality, better control, reduced energy and sustainability. This paper is an overview of what is happening in Europe and elsewhere and examines the literature to find that latest recommendations in the Code for Lighting issued by the SLL (Society of Light and Lighting) in the UK change previous demands for equal illuminance across a working plane to more specific and demanding criteria. There are recommendations for qualitative metrics and better distribution of light so as to enhance the visual appearance of interiors. European standards are also examined and the LENI (lighting energy numerical indicator) has been found to be a better way of reducing energy than installed load. New LED (light-emitting diode) lamp technology is examined and daylight is discussed in the context of these changing demands. It is found that lighting standards and design are changing for the better but that standards will need to evolve further if they are to ensure good quality lighting.展开更多
Energy used for industrial production, buildings and transport will be accumulated in Atmosphere and Earth land. Global use of energy is known and documented for a long period of time and proportion of fossil and rene...Energy used for industrial production, buildings and transport will be accumulated in Atmosphere and Earth land. Global use of energy is known and documented for a long period of time and proportion of fossil and renewable energy is also known. Calculated accumulated energy in Earth land from 1971 to 2018 corresponds to 40% of IPCC Global Energy Inventory and calculated Atmosphere temperature increase from 1971 to 2018 corresponds to 100% of actual measurements.展开更多
Numerous studies have demonstrated that commercial activities have significantly reduced during COVID-19,while there are few studies disclosing the consequent impacts on the energy consumption of commercial build-ings...Numerous studies have demonstrated that commercial activities have significantly reduced during COVID-19,while there are few studies disclosing the consequent impacts on the energy consumption of commercial build-ings.This study explores the changes in energy consumption of different types of commercial buildings in Sin-gapore under the impact of the pandemic,using commercial building energy performance data from 2017 to 2020(n=540).The sampled buildings include 93 hotel buildings,303 office buildings,106 retail buildings,and 38 mixed developments.The analysis mainly used linear regression and paired sample t-test.The results showed that relative to 2019,the mean energy use intensity(EUI)of sampled commercial buildings decreased by 56.77 kWh/m^(2)in the pandemic year(2020),a plunge of 19.9%.The extent to which the EUI of each type of commercial building is affected by the pandemic is found as:mixed development>retail>office>hotel.The study also identi-fied the factors that significantly influenced the EUI of commercial buildings before and during the pandemic.The results of the study complement existing knowledge about the factors influencing energy consumption in com-mercial buildings by considering the impact of the pandemic and furthermore contribute to the improvement of energy management in commercial buildings by providing directions for building energy efficiency approaches.展开更多
Embodied energy is a measure of the energy used in producing,transporting and assembling the materials for a building.Operational energy is the energy used to moderate the indoor environment to make it functional or c...Embodied energy is a measure of the energy used in producing,transporting and assembling the materials for a building.Operational energy is the energy used to moderate the indoor environment to make it functional or comfortable-primarily,to heat or cool the building.For many building geometries,the walls make the most significant contribution to the embodied energy of the building,and they are also the path of greatest heat loss or gain through the fabric,as they often have a greater surface area than the roof or floor.Adding insulation reduces the heat flow through the wall,reducing the energy used during operation,but this adds to the embodied energy.The operational energy is not only a function of the wall buildup,but also depends on the climate,occupancy pattern,and heating strategy,making an optimisation for minimum overall energy use non-trivial.This study presents a comparison of typical wall construction types and heating strategies in a temperate maritime climate.The transient energy ratio method is a means to abstract the heat flow through the walls(operational energy for heating),allowing assessment of the influence of walls in isolation(i.e.in a general sense,without being restricted to particular building geometries).Three retrofit scenarios for a solid wall are considered.At very low U-values,overall energy use can increase as the embodied energy can exceed the operational energy;current best practice walls coupled with low building lifetimes mean that this point may be reached in the near future.Substantial uncertainty is present in existing embodied energy data,and given its contribution to total energy use,this is a topic of urgent concern.展开更多
Consider the task of tracking the energy use of an entire city while also working to reduce it by 50%in 17 years.How would you go about tracking and verifying such reductions?Further,how would this be accomplished in ...Consider the task of tracking the energy use of an entire city while also working to reduce it by 50%in 17 years.How would you go about tracking and verifying such reductions?Further,how would this be accomplished in a city without a database of building-specific characteristics and no energy reporting law?To begin,let’s consider what this task would look like for one building.Where to start?Let’s try with a performance metric and point of comparison.Just as cars gauge performance by MPG,and pitchers by ERA,buildings can use Energy Use Intensity(EUI)as a performance metric.Measured in Energy/ft2/year,EUI standardizes energy use per square foot,allowing for comparison between many buildings.EUI is a snapshot of building performance over one year’s time.It is relatively easy to calculate a building’s EUI if their energy usage is known,but in order to gauge performance over a longer period,a constant comparison point must be established so that evaluation is consistent.Called the baseline,this comparison point can be established as a past year,a future goal,or the average performance of similar buildings.This paper covers the work of the Pittsburgh 2030 District team in formulating an energy performance baseline for each building in Downtown Pittsburgh for purposes of tracking energy use reduction towards the 50%reduction goals of The 2030 Challenge.Pittsburgh is a city with a large stock of aging buildings,without mandatory benchmarking laws,and no single publicly accessible real estate profile by property.Thus,the energy baseline methods included in this paper summarize efforts to create such an aggregated property characteristic database and associated energy baseline for Downtown Pittsburgh;it is the hope of the authors that these efforts will assist similar cities in mirroring 2030 District goal setting and achievement for building energy.展开更多
In recent years,large high efficiency and Net-Zero Energy Buildings(NZEB)are becoming a reality that are setting construction and energy benchmarks for the industry.As part of this significant effort,in 2018,Mohawk Co...In recent years,large high efficiency and Net-Zero Energy Buildings(NZEB)are becoming a reality that are setting construction and energy benchmarks for the industry.As part of this significant effort,in 2018,Mohawk College opened the 8,981 m^(2)(96,670 ft2)Joyce Centre for Partnership and Innovation(JCPI)building in Hamilton,Ontario;becoming Canada’s largest NZEB and zero-carbon institutional facility.The building integrated a high-efficiency design,construction materials,and technologies;as well as renewable energy technologies to significantly reduce its annual energy consumption and greenhouse gas emissions.Furthermore,the JCPI building was also designed as a living lab where students,faculty,researchers and industry are able to monitor and validate the performance of this state-of-the-art facility.The building was designed to have an energy use intensity of 73 kWh/m^(2)·year(0.26 GJ/m^(2)·year);hence,potentially consuming approximately 80%less energy than the average educational service building in Ontario.This paper gives an overview of the design criteria and technologies that were considered to achieve this innova-tive building.展开更多
This study develops a bottom-up model to quantitatively assess the comprehensive effects of replacing traditional petroleum-powered vehicles with natural gas vehicles(NGVs) in China based on an investigation of the ...This study develops a bottom-up model to quantitatively assess the comprehensive effects of replacing traditional petroleum-powered vehicles with natural gas vehicles(NGVs) in China based on an investigation of the direct energy consumption and critical air pollutant(CAP) emission intensity, life-cycle energy use and greenhouse gas(GHG) emission intensity of NGV fleets. The results indicate that, on average, there are no net energy savings from replacing a traditional fuel vehicle with an NGV. Interestingly, an NGV results in significant reductions in direct CAP and life-cycle GHG emissions compared to those of a traditional fuel vehicle, ranging from 61% to 76% and 12% to 29%, respectively. Due to the increasing use of natural gas as a vehicle fuel in China(i.e. approximately 28.2 billion cubic metres of natural gas in2015), the total petroleum substituted with natural gas was approximately 23.8 million tonnes(Mt), which generated a GHG emission reduction of 16.9 Mt of CO2 equivalent and a CAP emission reduction of 1.8 Mt in 2015. Given the significant contribution of NGVs, growing the NGV population in 2020 will further increase the petroleum substitution benefits and CAP and GHG emission reduction benefits by approximately 42.5 Mt of petroleum-based fuel, 3.1 Mt of CAPs and 28.0 Mt of GHGs. By 2030, these benefits will reach 81.5 Mt of traditional petroleum fuel, 5.6 Mt of CAPs and 50.5 Mt of GHGs, respectively.展开更多
Greenhouse-gas (GHG) emissions in China have aroused much interest, and not least in recent evidence of their reduction. Our intent is to place that reduction in a larger context, that of the process of industrializat...Greenhouse-gas (GHG) emissions in China have aroused much interest, and not least in recent evidence of their reduction. Our intent is to place that reduction in a larger context, that of the process of industrialization. A lengthy time perspective is combined with a cross-sectional approach-China plus five other countries-and addressed through two general models. The findings are salutary. First, they suggest that a diversified economic structure is consistent with diminished intensity in energy use. Secondly, and the obverse of the first, they imply that a diversified energy structure promotes reductions in CO2 emissions. Finally, one is led inevitably to the conclusion that, together, the findings point to a path for countries to transform their economies while at the same time undertaking to drastically moderate their energy use, switching from a pattern of heavy carbon emissions to one in which lighter carbon emissions prevail. The implications of such findings for environmental management are enormous.展开更多
文摘During metal machining, the satisfactoriness of cost-quality-time matrix convergence effectively depends on the supreme selection of cutting parameters. This study investigated the energy use minimisation and quality surface generation through optimised cutting parameters application, as sustainability enhancement during dry turning of EN19 material. Cutting parameter optimisation is a serious challenge confronting the machining industry as they strive to achieve low energy use and better component quality generation from their operations. The utility material, EN19, is a medium-carbon low alloy steel which typically gets applied in the manufacturing of multiple profiled cylindrical machine tool, rail locomotives and motor vehicle component parts, inter alia. Taguchi Full Factorial experimental plan was used to organise the empirical experiments. ANOVA and the main effects plot signal-to-noise ratio optimisation analysis were utilised in the study to establish the influence of process parameters on the response parameters—surface roughness and energy use. The aim was to investigate and determine the correlation of the machining strategy parameters with the outcome of low energy use and quality surface texture of the components as the cutting parameters were varied, and optimised for minimum surface roughness and energy use. Results of the extensive experimental study, produced optimum cutting speed, rake angle variation and feed rate which respectively influence the response parameters positively for energy use minimisation and improved surface quality. Validation experiments confirmed model findings.
文摘With the support by the National Natural Science Foundation of China,the research team led by Prof.Wei Chu(魏楚)and Prof.Zheng Xinye(郑新业)at the Department of Energy Economics,School of Economics,Renmin University of China,measures the inequality using the household energy
文摘National Association for Hydrogen Energy (NAHE) was established in 2003 to facilitate the effective integration of the Russian Federation into the world hydrogen economy. The priority for the Association is to create legislation and basic standards which necessary for the successful development of hydrogen energy, promote this sector to a large public and to support the development of those priority areas, where Russia has the best prospects to take a rightful place in the international division of labour (atomic hydrogen energy, fuel cells, hydrogen vehicles). Hydrogen Energy, National Association for Hydrogen Energy By now the Association has developed a draft technical regulation on security devices and systems
文摘Neutral particle energy spectra in the HT-7 tokamak are calculated by using the Monte Carlo method. It can reproduce the spectra measured in experiment. Differences of neutral particle energy spectra in higher and lower electron density plasma are discussed. Results show that the ion temperature given by neutral particle energy spectra is lower than the real ion temperature, but the deviation is within 10% if the ion temperature is less than 800 eV and thecentral chord-averaged electron density does not exceed 3 ×1013 cm-3. But for ion temperature higher than 1000 eV at the central chord-averaged density limit up to 5 ×1013 cm-3, the neutral particle energy spectra can still give the ion temperature within 10% deviation.
基金supported and funded by the California Department of Water Resources(DWR)
文摘The California Simulation of Evapotranspiration of Applied Water (CaI-SIMETAW) model is a new tool developed by the California Department of Water Resources and the University of California, Davis to perform daily soil water balance and determine crop evapotranspiration (ETo), evapotranspiration of applied water (ETaw), and applied water (AW) for use in California water resources planning. ETaw is a seasonal estimate of the water needed to irrigate a crop assuming 100% irrigation efficiency. The model accounts for soils, crop coefficients, rooting depths, seepage, etc. that influence crop water balance. It provides spatial soil and climate information and it uses historical crop and land-use category information to provide seasonal water balance estimates by combinations of detailed analysis unit and county (DAU/County) over Califomia. The result is a large data base of ETc and ETaw that will be used to update information in the new California Water Plan (CWP). The application uses the daily climate data, i.e., maximum (Tx) and minimum (Tn) temperature and precipitation (Pcp), which were derived from monthly USDA-NRCS PRISM data (PRISM Group 2011) and daily US National Climate Data Center (NCDC) climate station data to cover California on a 4 kmx4 km change grid spacing. The application uses daily weather data to determine reference evapotranspiration (ETo), using the Hargreaves-Samani (HS) equation (Hargreaves and Samani 1982, 1985). Because the HS equation is based on temperature only, ETo from the HS equation were compared with CIMIS ETo at the same locations using available CIMIS data to determine correction factors to estimate CIMIS ETo from the HS ETo to account for spatial climate differences. CaI-SIMETAW also employs near real-time reference evapotranspiration (ETo) information from Spatial CIMIS, which is a model that combines weather station data and remote sensing to provide a grid of ETo information. A second database containing the available soil water holding capacity and soil depth information for all of California was also developed from the USDA-NRCS SSURGO database. The Cal-SIMETAW program also has the ability to generate daily weather data from monthly mean values for use in studying climate change scenarios and their possible impacts on water demand in the state. The key objective of this project is to improve the accuracy of water use estimates for the California Water Plan (CWP), which provides a comprehensive report on water supply, demand, and management in California. In this paper, we will discuss the model and how it determines ETaw for use in water resources planning.
基金Project(2011BAJ01B05) supported by the National Science and Technology Pillar Program during the Twelfth Five-year Plan Period of China
文摘With rapid economy growth,building energy consumption in China has been gradually increased.The energy consumption and indoor environmental quality of 51 office buildings in Hainan Province,a hot and humid area,were studied through collection of verified data in site visits and field tests.The result revealed that,electricity accounted for 99.79% of the total energy consumption,natural gas 0.17%,and diesel 0.04%.The air conditioning dominated the energy use with a share of 43.18%,equipment in the particular areas 26.90%,equipment in the office rooms 11.95%,lighting system 8.67%,general service system 7.57%,and miscellaneous items 1.73%.Statistical method including six indicators obtained the energy consumption benchmark with upper limit of 98.31 kW-h/m2 and lower limit of 55.26 kW-h/m2.According to ASHRAE standard(comfortable standard) and GB/T 18883-2002(acceptable standard),the indoor environmental quality of 51 sampled office buildings was classified into three ranks:good,normal and bad.With benchmark of building energy consumption combined with indoor environmental quality,it was found that only 3.92% of sampled buildings can be identified as the best performance buildings with low energy consumption and advanced indoor environmental quality,and the buildings classified into normal level accounted for the maximum ratio.
文摘Two spherically symmetric non-singular black hole solutions in Moiler tetrad theory of gravitation have been obtained. Although the two solutions have the same form of metric (spherically symmetric nonsingular black hole), their energy contents are different. We use another method given by Gibbons and Hawking to calculate the energy content of these solutions. We also obtained different value of energy. Study the requirements of a satisfactory energymomentum complex given by Moiler we find that the second solution, which behaves as 1/√r, is not transformed as a four-vector under Lorentz transformation.
基金This work was supported/funded by the Ministry of Higher Education/University of TechnologyMalaysia under the Fundamental Research Grant Scheme(FRGS/1/2021/TK0/UTM/02/45).
文摘The literature that a lack of integration between the performance shaping factors(PSFs)and the energy management performance(EMP)is one of the critical problems that prevent performance improvement and reduces the power plant’s efficiency.To solve this problem,this article aims to achieve two main objectives:(1)Systematically investigate and identify the critical success factors(CSFs)for integration with PSFs and EMP;(2)Develop a novel modelling approach to predict the performance of power plants based on innovative integrated strategies.The research methodology is grounded on the theoretical and practical approach to improving performance.The Newcastle Ottawa Scale(NOS)was used to assess the quality of the literature that met the criteria.To ensure the reliability and accuracy of the proposed model,the researchers developed a hypothesis and evaluated the CSFs via a case study in the Iraqi power plants.The findings of this study succeeded in developing a novel modeling approach to predict the performance by integrating the CSFs of both the PSFs and EMP to increase the positive interaction and energy efficiency of power plants.The results confirmed the validity of the selected hypotheses and verified the positive and important relationship with the success and improvement of the performance in power plants.However,the lack of consistency and balance in the current studies indicates that the performance strategy in power plants did not receive sufficient attention and needs further investigations.
文摘High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner(AC)in warm and humid regions.This study aims to evaluate the techno-financial aspects of the AC-cooled greenhouse as compared to the evaporative cooled(EV-cooled)greenhouse in winter and summer seasons.Two quonset single-span prototype greenhouses were built in the Agriculture Experiment Station of Sultan Qaboos University,Oman,with dimensions of 6.0 m long and 3.0 m wide.The AC-cooled greenhouse was covered by a rockwool insulated polyethylene plastic sheet and light emitting diodes(LED)lights were used as a source of light,while the EV-cooled greenhouse was covered by a transparent polyethylene sheet and sunlight was used as light source.Three cultivars of high-value lettuce were grown for experimentation.To evaluate the technical efficiency of greenhouse performance,we conducted measures on land use efficiency(LUE),water use efficiency(WUE),gross water use efficiency(GWUE)and energy use efficiency(EUE).Financial analysis was conducted to compare the profitability of both greenhouses.The results showed that the LUE in winter were 10.10 and 14.50 kg/m^(2) for the AC-and EV-cooled greenhouses,respectively.However,the values reduced near to 6.80 kg/m^(2) in both greenhouses in summer.The WUE of the AC-cooled greenhouse was higher than that of the EV-cooled greenhouse by 3.8%in winter and 26.8%in summer.The GWUE was used to measure the total yield to the total greenhouse water consumption including irrigation and cooling water;it was higher in the AC-cooled greenhouse than in the EV-cooled greenhouse in both summer and winter seasons by almost 98.0%–99.4%.The EUE in the EV-cooled greenhouse was higher in both seasons.Financial analysis showed that in winter,gross return,net return and benefit-to-cost ratio were better in the EVcooled greenhouse,while in summer,those were higher in the AC-cooled greenhouse.The values of internal rate of return in the AC-and EV-cooled greenhouses were 63.4%and 129.3%,respectively.In both greenhouses,lettuce investment was highly sensitive to changes in price,yield and energy cost.The financial performance of the AC-cooled greenhouse in summer was better than that of the EV-cooled greenhouse and the pattern was opposite in winter.Finally,more studies on the optimum LED light intensity for any particular crop have to be conducted over different growing seasons in order to enhance the yield quantity and quality of crop.
基金This work was supported by the David and Lucie Packard Foundation in partnership with the Energy Foundation, US. Project (G - 0205 -06347)
文摘The Chinese government is developing biomass ethanol as one of its automobile fuels for energy security and environmental improvement reasons. The energy efficiency of the biomass-based fuel ethanol is critical issue. To investigate the energy use in the three biomass-base ethanol fuel systems, energy content approach, Market value approach and Product displacement approach methods were used to allocate the energy use based on life cycle energy assessment. The results shows that the net energy of corn based, wheat based, and cassava-based ethanol fuel are 12543MJ, 10299MJ and 13112MJ when get one ton biomassbased ethanol, respectively, and they do produce positive net energy.
文摘Residential energy consumption is varying considerably worldwide. In order to understand these variations, and thus design effective policies for energy reductions, one needs a better understanding of the different drivers behind these variations. A comparison of geographical areas with similar climate and socio-economic conditions has shown significant variations in residential energy consumption across otherwise comparable case studies. This research paper aims to identify cultural and historical parameters that contribute to these significant variations, including economic, environmental and social traditions related to local availability of natural resources. Furthermore, the transferability of these parameters is evaluated, taking into consideration local legislation and planning documents, and historic and socio-economic accessibility of resources. It is evaluated to which degree these parameters can be transferred and included into building assessment tools and policy documents for planning and transformation of sustainable urban neighborhoods.
文摘Lighting design is one of the fastest changing areas in building engineering. It has evolved significantly in recent years due to changing technology and demands for improved quality, better control, reduced energy and sustainability. This paper is an overview of what is happening in Europe and elsewhere and examines the literature to find that latest recommendations in the Code for Lighting issued by the SLL (Society of Light and Lighting) in the UK change previous demands for equal illuminance across a working plane to more specific and demanding criteria. There are recommendations for qualitative metrics and better distribution of light so as to enhance the visual appearance of interiors. European standards are also examined and the LENI (lighting energy numerical indicator) has been found to be a better way of reducing energy than installed load. New LED (light-emitting diode) lamp technology is examined and daylight is discussed in the context of these changing demands. It is found that lighting standards and design are changing for the better but that standards will need to evolve further if they are to ensure good quality lighting.
文摘Energy used for industrial production, buildings and transport will be accumulated in Atmosphere and Earth land. Global use of energy is known and documented for a long period of time and proportion of fossil and renewable energy is also known. Calculated accumulated energy in Earth land from 1971 to 2018 corresponds to 40% of IPCC Global Energy Inventory and calculated Atmosphere temperature increase from 1971 to 2018 corresponds to 100% of actual measurements.
文摘Numerous studies have demonstrated that commercial activities have significantly reduced during COVID-19,while there are few studies disclosing the consequent impacts on the energy consumption of commercial build-ings.This study explores the changes in energy consumption of different types of commercial buildings in Sin-gapore under the impact of the pandemic,using commercial building energy performance data from 2017 to 2020(n=540).The sampled buildings include 93 hotel buildings,303 office buildings,106 retail buildings,and 38 mixed developments.The analysis mainly used linear regression and paired sample t-test.The results showed that relative to 2019,the mean energy use intensity(EUI)of sampled commercial buildings decreased by 56.77 kWh/m^(2)in the pandemic year(2020),a plunge of 19.9%.The extent to which the EUI of each type of commercial building is affected by the pandemic is found as:mixed development>retail>office>hotel.The study also identi-fied the factors that significantly influenced the EUI of commercial buildings before and during the pandemic.The results of the study complement existing knowledge about the factors influencing energy consumption in com-mercial buildings by considering the impact of the pandemic and furthermore contribute to the improvement of energy management in commercial buildings by providing directions for building energy efficiency approaches.
文摘Embodied energy is a measure of the energy used in producing,transporting and assembling the materials for a building.Operational energy is the energy used to moderate the indoor environment to make it functional or comfortable-primarily,to heat or cool the building.For many building geometries,the walls make the most significant contribution to the embodied energy of the building,and they are also the path of greatest heat loss or gain through the fabric,as they often have a greater surface area than the roof or floor.Adding insulation reduces the heat flow through the wall,reducing the energy used during operation,but this adds to the embodied energy.The operational energy is not only a function of the wall buildup,but also depends on the climate,occupancy pattern,and heating strategy,making an optimisation for minimum overall energy use non-trivial.This study presents a comparison of typical wall construction types and heating strategies in a temperate maritime climate.The transient energy ratio method is a means to abstract the heat flow through the walls(operational energy for heating),allowing assessment of the influence of walls in isolation(i.e.in a general sense,without being restricted to particular building geometries).Three retrofit scenarios for a solid wall are considered.At very low U-values,overall energy use can increase as the embodied energy can exceed the operational energy;current best practice walls coupled with low building lifetimes mean that this point may be reached in the near future.Substantial uncertainty is present in existing embodied energy data,and given its contribution to total energy use,this is a topic of urgent concern.
文摘Consider the task of tracking the energy use of an entire city while also working to reduce it by 50%in 17 years.How would you go about tracking and verifying such reductions?Further,how would this be accomplished in a city without a database of building-specific characteristics and no energy reporting law?To begin,let’s consider what this task would look like for one building.Where to start?Let’s try with a performance metric and point of comparison.Just as cars gauge performance by MPG,and pitchers by ERA,buildings can use Energy Use Intensity(EUI)as a performance metric.Measured in Energy/ft2/year,EUI standardizes energy use per square foot,allowing for comparison between many buildings.EUI is a snapshot of building performance over one year’s time.It is relatively easy to calculate a building’s EUI if their energy usage is known,but in order to gauge performance over a longer period,a constant comparison point must be established so that evaluation is consistent.Called the baseline,this comparison point can be established as a past year,a future goal,or the average performance of similar buildings.This paper covers the work of the Pittsburgh 2030 District team in formulating an energy performance baseline for each building in Downtown Pittsburgh for purposes of tracking energy use reduction towards the 50%reduction goals of The 2030 Challenge.Pittsburgh is a city with a large stock of aging buildings,without mandatory benchmarking laws,and no single publicly accessible real estate profile by property.Thus,the energy baseline methods included in this paper summarize efforts to create such an aggregated property characteristic database and associated energy baseline for Downtown Pittsburgh;it is the hope of the authors that these efforts will assist similar cities in mirroring 2030 District goal setting and achievement for building energy.
文摘In recent years,large high efficiency and Net-Zero Energy Buildings(NZEB)are becoming a reality that are setting construction and energy benchmarks for the industry.As part of this significant effort,in 2018,Mohawk College opened the 8,981 m^(2)(96,670 ft2)Joyce Centre for Partnership and Innovation(JCPI)building in Hamilton,Ontario;becoming Canada’s largest NZEB and zero-carbon institutional facility.The building integrated a high-efficiency design,construction materials,and technologies;as well as renewable energy technologies to significantly reduce its annual energy consumption and greenhouse gas emissions.Furthermore,the JCPI building was also designed as a living lab where students,faculty,researchers and industry are able to monitor and validate the performance of this state-of-the-art facility.The building was designed to have an energy use intensity of 73 kWh/m^(2)·year(0.26 GJ/m^(2)·year);hence,potentially consuming approximately 80%less energy than the average educational service building in Ontario.This paper gives an overview of the design criteria and technologies that were considered to achieve this innova-tive building.
基金co-sponsored by the National Natural Science Foundation of China (71774095, 71690244 and 71673165)the Postdoctoral Science Foundation of China (2017M610096)the International Science and Technology Cooperation Program of China (2016YFE0102200)
文摘This study develops a bottom-up model to quantitatively assess the comprehensive effects of replacing traditional petroleum-powered vehicles with natural gas vehicles(NGVs) in China based on an investigation of the direct energy consumption and critical air pollutant(CAP) emission intensity, life-cycle energy use and greenhouse gas(GHG) emission intensity of NGV fleets. The results indicate that, on average, there are no net energy savings from replacing a traditional fuel vehicle with an NGV. Interestingly, an NGV results in significant reductions in direct CAP and life-cycle GHG emissions compared to those of a traditional fuel vehicle, ranging from 61% to 76% and 12% to 29%, respectively. Due to the increasing use of natural gas as a vehicle fuel in China(i.e. approximately 28.2 billion cubic metres of natural gas in2015), the total petroleum substituted with natural gas was approximately 23.8 million tonnes(Mt), which generated a GHG emission reduction of 16.9 Mt of CO2 equivalent and a CAP emission reduction of 1.8 Mt in 2015. Given the significant contribution of NGVs, growing the NGV population in 2020 will further increase the petroleum substitution benefits and CAP and GHG emission reduction benefits by approximately 42.5 Mt of petroleum-based fuel, 3.1 Mt of CAPs and 28.0 Mt of GHGs. By 2030, these benefits will reach 81.5 Mt of traditional petroleum fuel, 5.6 Mt of CAPs and 50.5 Mt of GHGs, respectively.
基金National Basic Research Priorities Programme of China No.2002CB412507+1 种基金 Research Program of the Ministry of Science and Technology of China No.973-2002CB412507
文摘Greenhouse-gas (GHG) emissions in China have aroused much interest, and not least in recent evidence of their reduction. Our intent is to place that reduction in a larger context, that of the process of industrialization. A lengthy time perspective is combined with a cross-sectional approach-China plus five other countries-and addressed through two general models. The findings are salutary. First, they suggest that a diversified economic structure is consistent with diminished intensity in energy use. Secondly, and the obverse of the first, they imply that a diversified energy structure promotes reductions in CO2 emissions. Finally, one is led inevitably to the conclusion that, together, the findings point to a path for countries to transform their economies while at the same time undertaking to drastically moderate their energy use, switching from a pattern of heavy carbon emissions to one in which lighter carbon emissions prevail. The implications of such findings for environmental management are enormous.